Measuring instrument



Jan. 19, 1943. -T R, HARRISON 2,308,687

MEASURING INSTRUMENT Original Filed May 20, 1936 2 Sheets-Sheet lINVENTOR. THOMAS R. HARRISON ATTORNEY.

1.9, 1943- T. R. HARRISON MEASURING INSTRUMENT Original Filed May 20,1936 2 Sheets-Sheet 2 INVENTOR THOMAS R. HARRISON BYQQWNW ATTORN EYthrough thelatter the element H.

provisions, the instrument shown in the drawings differs from, andcomprises improvements over previously known potentiometer instruments.I ee 7 In the instrument shown in the drawings allfy of the instrumentparts are normally contained within an instrument casing comprising acylindrical body B with a closed rear end and an open front end, and afront cover ordoor B connected to the body B at one side of the casingby a hinge B Most of the instrument parts x are supported by the casingbodyybut some of l the indicating parts are mounted on the casing doorB, and are moved away from theeother instrument parts when the casingdoor, is. turned into its open position, as is shownin Fig.5;

Preparatory to a more detailed description of a the mechanism, it isnoted that the instrument ment of the character disclosed should give avisual indicating of th value of the quantity measured, which is moreeasily read than the indication furnished by the angular position of thepen arm 1-K. t, For ,instance, if. the instrument is used to measuresome temperature or other condition of boiler operation, it isordinarilyvdesirable that the instrument should furnish an indication ofthe current value of the quantity measured which can be visuallyobserved from various points ,or stations in the boiler room.

To provide such an'indication, the instrument shown comprises ,a pointerL, actuated through suitable means by the element H to indicate thev'alue, of thefuuantity measured, on a ciri cular scale is carried bythe instrument adjacent the peripheryof .the chart K.

illustrated. includes means for periodically in, engagement with-theclamped pointerwA';

and for then angularly adjusting the' element H through the clutchdevice I to an extentand ine direction selectively dependent upon theposition'into which the device I has been ad justedby the feeler G. Theelement H includes cam surfaces fl 'and H through which theanguianmovementsbf the element givesultable corresponding movements tolevers K and L through which a pen arm K and an indicating .pointerLlare suitably, adjusted to'record and indicate, the existingvalueofflthethermocouple 40 yoltage'. l A continuously. operating relaymotor E rotates a cam shaitjEparallel to, but laterally displaced fromthe shaft HB,to thereby effect cyclicoper'ations relatively timjed'oi'the' pointer clamping mechanism, the feeler G, device 'I, and

furthersdetailed description oi the relay ,mechanism' is believed to beunnecessary herein sinceit is fully describedtin the parent *appll-;-,,cation 80,708, above mentioned. It is suificient to state thatfltheshaft H8 is cyelicallyrotated to positions corresponding to thevalue'ofthe conditionbeing measured and that the indicating means isadjusted therefrom in a'manner, now ,to be described.

K9 at'the front of the instrument carriedby a chart driving, member KBmounted in the frame member 131 and forming a part oi the 'power unitwhich is slowly rotated by th'e rnotor F, and ,a pen arm Kin front ofthe chart. Thearm K is fcarried in awell known manner through a yoke, Kby anfoscillating member K back of the chart and having an operatingarmK connectedby a link K tpfale'ver K carrying a rollerKJ engaging asuitably "shaped cam edge portion H of the element As the Iangularlposition of the elementI-I isvaried, in accordance with changesin the thermocouple ,voltageor other quantity measured the cam edge H?correspondinglyturns'the lever K and the pen arm K ',"sp that the latterrecords the value of the quantity measured on the chart K". i ,In manycases, it is desirable that an instru- 'Ihe ,recording provisiohsofthe'lnstrument shown in the drawings, comprise a circular-"chart B isin its closed position, and whichaccom.

, other, of the, latter.

The means shown, through which the pointer L 'is moved, comprises alever M, which is back 20 of the,chart,K', and isconveniently pivoted,

as shown on'the, shaft 'JB, and carries apin M engaging, a cam part ofthe element Hi "As will be apparent, the 'part engaged by the pin, M,may be the edge H through which the pen arm K is moved, butg to permitthe use ;of diilerent scale arrangements, as herein after described, the,leverM may well be given its movements by a separate cam 11*, as shownin'Fig.3.., e I

The pointer L is in, front" I of the chart K'; and.in accordance, withthe present'inventicn. is preferably mounted onhthe casing door formovement away from the chart when the door is;opened,iso.as not,to'interfere with, the replacement or adjustment of the chart; As shown,the pointer Li'is journalled ona supporting: stud, or shaftv Li carriedby a, bracket BL rigidly attached to the rim oriframe of the casingdoor; Bf, adiacentf the h n e connection "B? for the ettergltwnen tnescale LS eictends circularly about or the chart driving member. KB, gasshown; th e"' pivct L well be mounted in the bracket" BLi soas ftpbeboaxial, orisubstantially so, with the member KB when thedoo'r B5 isin its closed position. Rigidly secured to the, pointer Lus pinion L inmesh with a,,gear[segment;L? seemed to the adjacent end of alever Lpiyoted on the bracket BL at, L, by eccentric adjusting and clampingmeans including screws h angi L and aslot hi in thearm L The pivot};"iscoaxial with the, shaft JB fwhen the. asi g doorf B is in its closedposition} As the lever L isro'tated between its itwo dottedQlineliositions shown in Fig. d thetindicating Leno; oi he 1 pointer L ismoved; along th scale i$irom one end tothe The end of the lever'L remotefrom-the pinion L and the end of the leverM remote fromits supportingshaft JB. extend into proximlty with the hinge connection B andareconnected by a flexible connection, which extends past the edge ofthe chart K and through which angular movements of the lever- M aboutthe supporting shaft JB, give corresponding anew lar movements to thelever L when the dommodates the relative movement-s of the two 'tioncomprises an arm levers occurringwhenthe door B'is movedbe tween itsclosed and open positions.

In the iorm shown, the said flexible connec- L pivotally connected tothe lever I)", an arm M pivotally connected to leverM, and a. universalJoint connection be 76 tween the twomag-me axis-oi the pivotal con- 1opposed portions of the ball M The means described for giving theirrespective "suppressed scale rigidly connected to the free end of thearm NP and held between transverse projections 11" y from the arm L atits free end, which are formed with small apertures L to receivediametrically movements to the pen arm-K and indicator arm L, are simpleand effective from the mechanical standpoint, and the manner in whichthe indicator pointer L is mounted and actuated, is especially desirablebecause it permits or a pointer length as great as the chart diameter,without interfering with chart adjustments or replacements.

Furthermore, the means through which the pen arm K and the pointer L aregiven' their movements, make it readily feasible to give to themovements of each, the particular scale valhas most desirable fromthepractical standpoint for any given use of the instrument. The'contour ofthe cam edge 1-1 shown in Fig. 1, is such as to progressively move thepen armK outwardly from the center to the periphery of the chart K? asthe value of the quantity measured increases and the contact 8 iscorrespondingly adjusted in the counter-clockwise direction. If themovement 0! the pen from its initial central position on the chart tothe periphery of the latter, corresponds to the movement of the contact8, as the value 0! the quantity measured increases from zerov to itsmaximum value, 'therecord produced is what is sometimes referred to as afull scale record.

In some cases, however, what is known as a record is practicallydesirable, and is obtainable with a simple modification o! the apparatusshown in Fig. 1. For example-,-, if the part of the element H carryingthe can.

edge H shown in Fig. 1,-is replaced by a part HA and cam parts HA" andHA detachably connected thereto, as shown in Fig. 2, a suppressed scalerecord will be produced as a result of the contour of the cam edgecollectively formed by the parts HA, HA and HA, and engaging the minimumvalue below said intermediate, value. As the value increases from saidintermediate value to a second hole BA in the part HA, the pen actuatinglever roller K will then move along the hub portion HA or the part HA asthe quantity measured increases from zero to 'acertain intermediatevalue,..and if the hubportion is concentric with the shaft HB, .the penarm will be at its position on the chart for values intermediate value,and the roller K", moves along the cam edge the pen arm will move fromitszero value positlon on thelchart to the periphery of .the latter,and. thereafter, as mediumtity measured continuesto increase invalue,the

pen arm will remain at the periphery of the chart. -With.the arrangementjust described, the

. recorder the-value ofjthe quantity measured is i suppressed, exceptfor values' between'the' two intermediate values mentioned.

secured with the screw hole HA in register with It with. the part HAremoved, the part HA is the screw hole-HA ,of the part, HA, only valuesof the quantity measuredbetween its maximum value and a certainintermediate value will be recorded.

Which scale portion or portions of the record are advantageouslysuppressed in any given case,

will depend upon conditions of use. The increased accuracy and ease ofreading of the rec- ..ord obtainable with the suppressed scale eflect,

areplainly apparent, sincethe eflect of moving the pen entirely acrossthe chart for a portion only oi the full range of variation in value ofthe quantitymeasured, is to "open" the record formed or,stateddifferentlmis to increase the distancebetwcen two scale marksrepresenting two successive scale units.

Instead of totally suppressing some portion or portions of, the scale,it maybe desirable: in a some cases to make the contour. of thecontrolling cam such as, to open upthe scale for a certrain andpractically important fractionpt the range of value variation andcorrespondingly closing but not entirely suppressing the'scale ofanother portion or portions of the range of value variations. Thisresult is, secured with the cam edgeH shown in Fig.1,which has its edgeso pen arm actuatingdever roller K". As is plainly all portions of theedge enconcentric with the shaped that aportion H thereof, engaging theroller K during the angular movement of the element H through arelatively small intermediate portion of its total range of movement, isadapted to give the pen arm a major portion of its movement between, thecentral portion and r periphery orthe chart Ki. With the parts so acertain predetermined value much smaller than the value of the quantitycorresponding to the full angular movement of the element H. As thequantity increases in value above said prede- 'termined value,'theposition of the pen arm, then at the periphery of the chart, will notchange. The record thus produced is commonly referred to as a.suppressed scale record.

arranged, the initial and final portions of the movement of the pen armfrom the centralportionto-the periphery of the chart will actuallyrecordv the corresponding variations in the value oi thequantitymeasured, but will record those variations in accordance with a scalemuch' closer or smaller, than the scale of the record formed whiletheroller K engages the, cam edge portion The supp sed scale effect isdesirable in indicating, as well as in recording, values of the Insteadof suppressing the record except for values of the quantity measuredbetween 'zero and said predetermined value, some other record portion orportions may be suppressed. For example, it with the apparatus shown inFig. 2 the part HA is removed, and the part HA is adjustedcounter-clockwise relative to the part HA, so that it may be secured tothe latter by the screw HA with the latter passing thro sh the screwquantity measured- For. example, if it be assumed that theinstmmentishown were intended to measure a furnace temperature varyingfrom a minimum-oi zeroto amaxlmum of 1200", but

which under all normal operating conditions varies only between aminimum of 800 and a maximum of 1000", there would be an obviousadvantage, in some cases, in shaping the cam H so that the pointer L ismoved from one end to 75 the other of the scale LS, as the temperatureof the latter to turnabout an axis at a distance from said hingeconnection, one end of said lever being adjacent said hinge connection,measur-- ing means within said casing body including a part adjacentsaid hinge connection and adapted for movement in the. general directionof the axis of said connection in accordance with variations in thevalue of the quantity measured, and a flexible connection between saidpart and lever end adapted to accommodate bodily movement ot-said leverrelative to said part when the door measured, while recording thevarying values of the quantity through a portion only of its total rangeof variation.

Whether or not the suppressed scale effect is obtained, with the meansfor adjusting either the pen'arm or the pointer L, the described meansfor giving the pen arm and pointer their movements as the element H isadjusted, aredesirable because of their simplicity and efiectiveness andbecause they permit of the ready use of cam contours making thedeflections of either pen arm or pointer linearly proportional to thechanges in value of the quantity measured,

even though that value is not in linear proportion to the angularmovement of the member H occurring as the measured quantity changes invalue.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of my invention now known to me,it will be apparent to those skilled in the art that changes may be madein the form of the apparatus disclosed without departing from the spiritof my invention as set forth in the appended claims, and that in somecases certain features of my invention may sometimes be used toadvantage without a corresponding use of other features.

Having now described my invention, what I claim as new ad desire tosecure by Letters Patent is:

1. A measuring instrument comprising a casing including a casing bodyhaving a front opening, a door normally closing said opening, a

hinge connection between said body and door at one side of said opening,exhibiting means including a lever mounted on said door at the inherside of the latter to turn about an axis at a distance from said hingeconnection, one end of said lever being adjacent said hinge connection,measuring means within said casing body including a part adjacent saidhinge connection and adapted for movement in the general direction ofthe axis of said connection in accordance with variations in the valueof the quantity measured, and a flexible connection between said partand lever end adapted to accommodate bodily movement of said leverrelative to said part when the door is moved away from, and returned tois moved away from, and returned to its closed position and throughwhich, when the door is in its closed position, movements of said partgive corresponding angular movements about said axis to said lever, apointer pivotally mounted on said door at the inner side of the latter,and an operating connection between said lever and pointer through whichsaid angular lever movements give said pointer angular movementsproportional to, but of greater magnitude than the movements of saidlever.

3. In an instrument adapted to measure and exhibit the value of avariablecondition comprising a casing, a door for said casing hingedthereto. measuring means located in said casing, an exhibiting membermovably mounted upon said door to be moved with said door as the door isopened or closed, and mechanism operative to move said exhibiting memberin response to measurements made by said measuring means.

4. In a measuring instrument, the combination of a casing, measuringmeans located in said casing, a door for said casing. provided with awindow, an exhibiting element pivotally attached to the interior of saiddoor ,to be visible through said window, means to hinge said door uponsaid casing, and drive means between said measuring means and exhibitingelement, said drive means being provided with a hinge portion wherebysaid drive connection is not broken as the door is moved around itshinge relation to the casing.

5. In a measuring instrument, the combination of an instrument easing,measuring means lo-' 'cated therein, a door. for said casing hingedthereto, said door being provided with a window,

its closed position and through which when the ing including a casingbody having a front openj ing, a door normally closing said opening, ahinge connection between said body and door at one side of said opening,exhibiting means including a lever mounted on said door at the innerside an exhibiting element, means to mount said element upon theinterior of said door and for rota-tive movement relative thereto,'saidelement being visible through said window, connecting means between saidmeasuring means and said element whereby the latter is moved inproportion to measurements made by the former, and hinge means formingpart of said drive means, the hinge means being located near the doorhinge so that the two will work together.

6. In an instrument adapted to measure and exhibit the value of avariable condition, the combination of an instrument casing having ameasuring means located therein, a door for said casing, hinges tosupport said door on the casing, an exhibiting element to indicate thevalue of the condition. as measured by the measuring meansmounted'for'movemenlt on the door, and Jointed drive means between saidmeasuring means and said element whereby the latter may be driven by theformer in any position of said door- .TnoMAsR. HARRISON.

